The invention relates to an air inlet for a heating or air-conditioning system of a motor vehicle having at least one air inlet opening which is arranged in an area below a windshield in which a ram pressure occurs during the drive of the motor vehicle. Certain embodiments relate to such system having at least one air inlet opening which, in an area below a windshield, is arranged laterally of a vehicle center plane.
In the case of the known air inlets, a blower is used when the vehicle is stopped and at a low speed of the vehicle in order to generate an air throughput in the interior of the motor vehicle, while, as the driving speed increases, a ram pressure is generated in the area below the windshieldxe2x80x94the so-called cowlxe2x80x94by means of which ram pressure the outside air automatically enters the heating or air-conditioning system. This ram pressure is a function of the speed, so that, at higher vehicle speeds, the air inlet must be throttled in order to counteract undesirably high flow rates in the vehicle interior. The throttling can take place manually, as known, for example, from German Patent Document DE 44 14 036 A1 (corresponding to U.S. Pat. No. 5,645,479), or by means of an automatic speed-dependent control. The throttling causes additional expenditures, particularly in the case of the automatic control which is to be preferred for reasons of comfort and where precise low-hysteresis kinematics are required in order to achieve a precisely reproducible position of the throttle valve because only very small passage cross-sections remain at high vehicle speeds. In addition, the cross-sections, which are highly throttled at higher vehicle speeds, may be the starting point of noises in the air inlet area.
In many vehicles, the air inlets are arranged in the lateral frame area of the windshield because a lower ram pressure occurs here, as illustrated, for example, in the representation of FIGS. 1 and 2 of French Patent Document FR 1,165,665 A. Nevertheless, at higher vehicle speeds, as a rule the ram pressure is so high also in the case of exterior air inlets that a throttling is required.
It is an object of the invention to provide a simply constructed air inlet for a motor vehicle, in the case of which the ram pressure is essentially independent of the vehicle speed.
This object is achieved according to certain preferred embodiments of the invention by providing an air inlet for a heating or air-conditioning system of a motor vehicle, having at least one air inlet opening which is arranged in an area below a windshield in which a ram pressure occurs during the drive of the motor vehicle, wherein a device is provided which partitions off the air inlet opening with respect to an area with a relatively high ram pressure and simultaneously causes the air supply from an area of the motor vehicle in which a relatively low pressure exists during the drive of the motor vehicle. This object is achieved according to other preferred embodiments by providing an air inlet for a heating or air-conditioning system of a motor vehicle, having at least one air inlet opening which, in an area below a windshield, is arranged laterally of a vehicle center plane, wherein a device is provided between the air inlet opening and the vehicle center plane, which device partitions off the air inlet opening with respect to air flows extending approximately transversely to a vehicle forward driving direction.
According to certain embodiments of the invention, the air inlet opening is insulated with respect to the area in which an excess pressure toward the vehicle interior forms during the drive of the motor vehicle, and the outside air is fed from an area with a low pressure level, such as the lateral area of the cowl of the vehicle body where, during the driving of the motor vehicle, a lower ram pressure occurs with respect to the vehicle interior (see French Patent Document FR 1,165,665 A). As the result, the pressure level at the air inlet opening is reduced, so that, as the vehicle speed rises, the air throughput does not increase or increases only relatively slightly. In view of the fact that, at higher driving speeds, a slightly increased air throughput is even desirable, in the case of the air inlet according to the invention, a ram air flap can be eliminated.
The system according to the invention comprises, for example, of a covering over the air inlet opening which is open only toward a side area of the vehicle body.
In modern motor vehicles, the air inlet openings are often situated in a covered manner in the area below the rearward end sections of the front flap. In the case of certain preferred embodiments of the invention, the invention can be implemented in a particularly simple manner by inserting a separating wall for sealing off the gap between the front flap and the windshield. Naturally, a partition of the duct cross-section toward the vehicle center is also required in order to insulate the air inlet opening with respect to this area of a high ram pressure. The partition according to the invention is hardly visible from outside the vehicle and can be provided at low expenditures in the case of new vehicle models as well as retrofitted in the case of existing vehicles.
Below the rearward end section of the front flap, the windshield wipers for cleaning the windshield are in many cases arranged in a hidden manner. In the case of windshield wipers constructed in pairs, the driving axis of the driver-side wiper is as a rule arranged on the exterior of the vehicle so that, in the case of a construction of the invention according to certain preferred embodiments, the partition extending above the air inlet opening must be provided with openings for the passing-through of the windshield wiper. In certain preferred embodiments, it is provided that an air inlet on the driver side be eliminated and a correspondingly dimensioned air inlet be provided only on the front passenger side.
While naturally a flow extending approximately in the driving direction flows against the center area of the windshield of a motor vehicle and the air flow flows off almost completely via the vehicle roof, so that the highest ram pressure occurs in the center below the windshield, a lateral flow also increasingly takes place around the lateral areas of the windshield because the air flow flows partially off in the direction of the vehicle side areas. As a result, a decreasing ram pressure occurs in the direction of the exterior side of the vehicle. As a result of the pressure difference between the vehicle center and the exterior side of the vehicle, an air flow extending transversely to the driving direction occurs in the area below the windshield. Here preferred embodiments of the invention provide a device for partitioning off this flow extending transversely to the driving direction. As a result, an exterior air inlet opening is insulated from the xe2x80x9ctransverse flowxe2x80x9d and thus a clear reduction is achieved of the dependence of the air throughput in the heating or air-condition system from the driving speed.
In the case of motor vehicles whose air inlet openings are arranged in a hidden manner in the area below the rearward end sections of the front flap, preferred embodiments of the invention can be implemented in a particularly simple manner by inserting a transverse wall into the duct below the windshield formed by the front-flap and other adjacent components. This division of the duct is hardly visible from outside the vehicle and can be provided at low expenditures in the case of new vehicle models as well as retrofitted in the case of existing vehicles.
In addition to the partitioning walls according to the above described embodiments, further partitioning can be provided, for example, if the air inlet opening is not situated sufficiently far on the exterior side of the vehicle. Such additional partitioning walls also prevent backflows from the windshield and disturbing air swirls at the air inlet opening.
By means of a further development of preferred embodiments of the invention wherein the device is provided with a sealing device in an area in which displaceable connection parts adjoin the device, an improved sealing-off of the air inlet area is achieved, particularly with respect to a displaceable front flap.
According to the type of the motor vehicle, under certain circumstances, a relatively high pressure level may also still exist in the lateral areas of the cowl. In such cases, a further advantageous development of preferred embodiments of the invention, wherein the air inlet opening is connected with an area of the motor vehicle in which a vacuum occurs during the drive of the motor vehicle, according to which a connection can be established to a lateral area of the vehicle body of the motor vehicle. As generally known and also illustrated in French Patent Document FR 1 165 665 A, FIG. 1, during the drive of the motor vehicle, a vacuum is present at the lateral surfaces of the vehicle body. By means of the coupling of this area of the air inlet opening according to the invention to this lateral area (or another area with a low pressure level), the pressure level at the air inlet opening is significantly lowered. As a vacuum-carrying area, the area of the door gap at the A-column can, for example, be used. In the case of vehicles, particularly sportscars, which have recesses (so-called xe2x80x9cgillsxe2x80x9d) in the lateral area of the fenders, this area of the fender can also be connected with the air inlet. As a rule, the coupling to the lateral area of the vehicle body takes place by correspondingly designed vehicle body parts and sealing devices. As an alternative to such a duct xe2x80x9cbuiltxe2x80x9d by means of correspondingly shaped motor vehicle parts, for example, a separate tube can also establish the connection to the lateral areas of the vehicle body.
A possible embodiment of the invention is illustrated in the drawing and will be explained in detail in the following.